When London 2012 organisers put their final batch of tickets on general sale on Wednesday, they will again confront two issues that have dogged the fraught process so far.

On one hand, they will hope Ticketmaster's technology, a constant source of concern, can cope with the final onslaught of demand. On the other, having made bold assertions that the Games will sell out, they face an uphill challenge to shift 1.4m remaining football tickets.

Football tickets have sold so slowly that it is almost certain fans will be able to buy them for many matches on the day, while Lord Coe, chairman of the organising committee (Locog), has refused to rule out giving them away.

At the start of the most recent sales window, only 11,000 tickets had been sold to the opening action of the Games – Team GB's women taking on New Zealand at the 72,500-capacity Millennium Stadium in Cardiff on 25 July.

However, while football sales have been sluggish, competition to see rhythmic gymnastics, handball and the other 23 Olympic sports has been fierce – at prices of £20-£2,012.

That demand has created huge challenges. Aside from technical problems, the loudest criticisms have been over ticket allocation and transparency.

Locog claims the allocation of tickets to officials and sponsors that angers many members of the public is one of the conditions to which London had to agree to stage the Games. In all, 6.6m of the 8.8m available tickets will go to the British public. Of the remainder, about 1.1m are sold overseas and the rest go to sponsors and hospitality providers.

Coe and his executives have been resolute in the face of public and political pressure. They say there is no point giving a venue by venue breakdown of how many tickets are available to the public in each price category until after the Games. It is a movable feast, they argue, due to the constantly shifting seating configurations.

And besides, they say, it depends how you define "the public" – some British buyers have secured tickets from European sellers and many sponsors are giving away their allocations in competitions.

But the overriding impression remains that the real reason they will not divulge the numbers is because they make for pretty embarrassing reading. For the 100m final, for example, just 29,000 seats of the official capacity of 80,000 are made available to the public.

There are only actually 58,000 tickets available in the first place once "seat kills" for the big screens, media positions and the like have been catered for. Around half go to the British public.

The situation is similar in the velodrome, but the numbers much smaller. On the biggest nights when Sir Chris Hoy and Victoria Pendleton will be aiming for glory, as few as 2,250 tickets will be taken by the public.

In the face of their continued refusal to break down the figures, London Assembly members accused organisers of running a "closed oligopoly" with a "chronic lack of transparency". The problems were exacerbated by the fractured relationship between Locog and Ticketmaster, the world's biggest ticketing company.

When the ticketing platform fell over in January, Locog was quick to blame Ticketmaster. Insiders at the company have claimed Locog has been an erratic client.

The original ballot, which saw 1.9m people make 22m applications, highlighted the scale of demand but also provoked criticism. Although the statistics proved otherwise, it gave the impression the rich could spread their bets by applying for dozens of tickets while others missed out.

Then came technical problems during a hastily arranged "second chance sale" in June during which an unwieldy Ticketmaster system first crawled to a halt, then took payment from 20,000 people but assigned them no tickets. The most embarrassing technical snafu came at the start of this year when a resale scheme flagged by organisers as a customer service coup turned into a PR nightmare.

Locog was forced to close the website after it collapsed as hundreds of thousands of people chased handfuls of tickets listed for resale.

Even the most recent batch of sales, offering 928,000 tickets to those who missed out in the opening two rounds, drew many complaints – despite organisers claiming it proceeded smoothly.

Some were annoyed they had to play "hunt the ticket" – endlessly clicking on apparently available options until their payment was accepted. Others believe Locog is hiding behind its status as a private company to avoid handling complaints properly.

There is potential for further embarrassment when the 500,000 remaining tickets go on general sale on Wednesday on a first come, first served basis. Organisers warned that customers could wait more than half an hour in peak periods.

On Tuesday night a Ukrainian Olympic official, Volodymyr Gerashchenko, was suspended following allegations by the BBC that he offered to sell up to 100 tickets for cash. Ukraine's committee received about 2,900 tickets in its official Olympic allocation.

It is illegal to sell the tickets on the black market, with fines of up to £20,000. Gerashchenko said he never planned to sell tickets in the UK.

Ticket resale site Viagogo predicted the Wednesday sale would provoke the biggest rush since the Take That reunion tour, with 25,000 tickets a minute being snapped up.

To guide potential buyers, Locog released a list of sports that have sold out, including events in the aquatics centre, the main stadium and the velodrome.

Aside from paying for a hospitality ticket (at up to £6,500) or one bundled with a short break from Thomas Cook, the only way to see those sports will be to try to secure one of the 200,000 tickets to be released for sale through public box offices once the final seat configurations are decided.

Attention will then turn to the battle to shift those football tickets and the embarrassing possibility of swaths of empty seats.

There is also the technical complexity of ressurecting the resale scheme that caused all the problems earlier this year and ensuring unused sponsors' tickets find their way into the hands of the public. Not to mention inevitable issues around touting and scam websites.

Coe and Locog chief executive Paul Deighton have expressed sympathy for those who missed out and suggested disappointment was a simple case of supply and demand.

Yet some of the errors were avoidable. Sir Keith Mills, the Locog deputy chairman who owned a large ticketing company in the late 1990s, admitted Ticketmaster had "struggled" and confessed communication with the public could have been better.

"When you're selling 10m tickets for a thousand different events and you've got massive demand, the technical complexity is enormous," he said.

"Ticketmaster did struggle. They had technical glitches and software glitches and difficulty dealing with some of the high volumes. But relative to the overall project they were really quite small."

Ultimately, Locog will point to the plaudits they have received from the IOC in selling out stadiums for sports that traditionally struggle to draw crowds, while hitting its revenue targets with ease.

Tickets contribute about £650m towards Locog's £2bn privately raised budget for staging the games. Privately, they say they would far rather deal with the consequences of overdemand than be struggling to balance the budget.

Mills, like Coe and Deighton, believes they have made it through with public goodwill intact as tickets start arriving this week. "Do I think we have delivered the fairest possible system? I absolutely do. We got it about as right as we could. We wanted to hit our revenue targets, we wanted full stadiums and we wanted to treat everyone as equally as we could," Mills said.